fWAR versus rWAR:
During 2010, Baseball-Reference unveiled a new feature: current and historical WAR values on each of its player pages. This WAR (referred to as rWAR) uses the same framework as FanGraphs’ version (fWAR), but has three main differences:
1. Pitcher Value: fWAR relies totally on FIP, making it a defense-independent metric, while rWAR adds in defensive runs saved as well.
2. Calculating Defense: Each system uses a different defensive metric. fWAR uses UZR, while rWAR uses TotalZone (developed by Sean Smith). UZR is more accurate but is only available from 2002 onward, while TotalZone values can be calculated for any player in baseball history.
3. Baserunning: rWAR includes this, while fWAR doesn’t.
As a result of these differences, rWAR values typically come in lower than fWAR values, meaning a 6 rWAR is more impressive than 6 fWAR. For more on the differences between fWAR and rWAR, please read these links: The Book Blog discussion, On Fielding Differences, and On Scaling.
fWAR is available on FanGraphs for any year in baseball history, but it is only calculated using UZR from 2002 onward. Any fWAR values earlier than that use TotalZone.
rWAR is available on Baseball-Reference for any year in baseball history.